In baseball, the head coach of a team is called the manager (or more formally, the field manager); this individual controls matters of team strategy on the field and team leadership. The manager sets the line-up and starting pitcher before each game as well as making substitutions throughout the game. How much control a manager takes in player strategy varies from one manager to another. Some managers control pitch selection, defensive positioning, decisions to bunt/steal/pitch out, etc., while others leave these decisions to a player's or assistant coach's discretion. Most find a balance somewhere in the middle.
In modern baseball the field manager is normally subordinate to the team's general manager, who among other things is responsible for personnel decisions, including hiring and firing the field manager. However, the term manager used without qualification almost always refers to the field manager, while the general manager is often called the GM.
In his comedy routine "Baseball and Football," George Carlin observes that only in baseball does the manager have to wear the same uniform the players do.

Current MLB managers